Rain brings relief, wets catchment but little inflow

Rain brings relief, wets catchment but little inflow

Much-needed rainfall in areas of the Sydney catchment and regional NSW will increase the likelihood of future inflows but have little immediate impact on WaterNSW dam storage levels.

Sydney catchment

In the Sydney catchment, rainfall prompted some tributary flows, but these have largely peaked and not generated any notable dam inflows.

Warragamba dam storage has only received 250 megalitres (ML) from a rain event that was largely coastal.

The exception was the Shoalhaven where Tallowa Dam could receive inflows of up to 1000 ML from tributary flows in the Kangaroo Valley that briefly peaked at a rate of 1400 megalitres per day.

The wet catchment and BoM predictions of a minor rain event next week raise the possibility of further inflows into metropolitan storages. The rain is also likely to temporarily reduce urban demand in the Sydney.

Regional NSW

Sporadic rain events across the regional NSW brought much-needed relief to landholders and communities struggling with drought but will have little short-term impact on water security.

Heavy falls occurred in the central west – notably the Macquarie Valley – and the state’s Far West, and Hunter regions while to the north and south lighter, patchy falls will leave the water security situation largely unchanged.

Heavy rainfall in parts of the central west did not reach key catchment zones and is unlikely to generate inflows of any significant volume into either Burrendong or Wyangala Dams.

The rain will reduce irrigation demand in these areas and wetter ground in catchment areas will increase the likelihood that any follow-up falls will result in run-off reaching storages.

In the state’s Far West Menindee (~50mm), Broken Hill (~35mm) and Pooncarie (~20mm) received welcome falls.

WaterNSW will continue to monitor river gauging and storage levels in coming days to assess the full impact of the rainfall.